mirror of https://git.ffmpeg.org/ffmpeg.git
mp3enc: write Xing TOC
Based on the code by: Peter Belkner <pbelkner@snafu.de>, Michael Niedermayer <michaelni@gmx.at>, Clément Bœsch <clement.boesch@smartjog.com>, Reimar Döffinger <Reimar.Doeffinger@gmx.de>, and Tobias Rapp <t.rapp@noa-audio.com> Alex Converse <alex.converse@gmail.com> Signed-off-by: Anton Khirnov <anton@khirnov.net>
This commit is contained in:
Anton Khirnov
parent
ca8e39dd0d
commit
7040c9fac2
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@ -74,12 +74,27 @@ static int id3v1_create_tag(AVFormatContext *s, uint8_t *buf)
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return count;
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}
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#define XING_NUM_BAGS 400
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#define XING_TOC_SIZE 100
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// maximum size of the xing frame: offset/Xing/flags/frames/size/TOC
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#define XING_MAX_SIZE (32 + 4 + 4 + 4 + 4 + XING_TOC_SIZE)
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typedef struct MP3Context {
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const AVClass *class;
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ID3v2EncContext id3;
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int id3v2_version;
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int write_id3v1;
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int64_t nb_frames_offset;
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/* xing header */
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int64_t xing_offset;
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int32_t frames;
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int32_t size;
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uint32_t want;
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uint32_t seen;
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uint32_t pos;
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uint64_t bag[XING_NUM_BAGS];
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int initial_bitrate;
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int has_variable_bitrate;
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/* index of the audio stream */
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int audio_stream_idx;
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@ -92,15 +107,17 @@ typedef struct MP3Context {
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static const uint8_t xing_offtbl[2][2] = {{32, 17}, {17, 9}};
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/* insert a dummy frame containing number of frames */
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/*
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* Write an empty XING header and initialize respective data.
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*/
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static void mp3_write_xing(AVFormatContext *s)
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{
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MP3Context *mp3 = s->priv_data;
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AVCodecContext *codec = s->streams[mp3->audio_stream_idx]->codec;
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int bitrate_idx = 1; // 32 kbps
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int32_t header;
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MPADecodeHeader mpah;
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int srate_idx, i, channels;
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int bitrate_idx;
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int xing_offset;
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int ver = 0;
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@ -132,6 +149,9 @@ static void mp3_write_xing(AVFormatContext *s)
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return;
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}
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/* 64 kbps frame, should be large enough */
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bitrate_idx = (ver == 3) ? 5 : 8;
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/* dummy MPEG audio header */
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header = 0xff << 24; // sync
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header |= (0x7 << 5 | ver << 3 | 0x1 << 1 | 0x1) << 16; // sync/audio-version/layer 3/no crc*/
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@ -141,17 +161,78 @@ static void mp3_write_xing(AVFormatContext *s)
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avpriv_mpegaudio_decode_header(&mpah, header);
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av_assert0(mpah.frame_size >= XING_MAX_SIZE);
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xing_offset = xing_offtbl[ver != 3][codec->channels == 1];
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ffio_fill(s->pb, 0, xing_offset);
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mp3->xing_offset = avio_tell(s->pb);
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ffio_wfourcc(s->pb, "Xing");
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avio_wb32(s->pb, 0x1); // only number of frames
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mp3->nb_frames_offset = avio_tell(s->pb);
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avio_wb32(s->pb, 0);
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avio_wb32(s->pb, 0x01 | 0x02 | 0x04); // frames / size / TOC
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mpah.frame_size -= 4 + xing_offset + 4 + 4 + 4;
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mp3->size = mpah.frame_size;
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mp3->want = 1;
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avio_wb32(s->pb, 0); // frames
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avio_wb32(s->pb, 0); // size
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// TOC
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for (i = 0; i < XING_TOC_SIZE; i++)
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avio_w8(s->pb, 255 * i / XING_TOC_SIZE);
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mpah.frame_size -= 4 + xing_offset + 4 + 4 + 4 + 4 + XING_TOC_SIZE;
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ffio_fill(s->pb, 0, mpah.frame_size);
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}
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/*
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* Add a frame to XING data.
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* Following lame's "VbrTag.c".
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*/
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static void mp3_xing_add_frame(MP3Context *mp3, AVPacket *pkt)
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{
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int i;
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mp3->frames++;
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mp3->seen++;
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mp3->size += pkt->size;
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if (mp3->want == mp3->seen) {
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mp3->bag[mp3->pos] = mp3->size;
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if (XING_NUM_BAGS == ++mp3->pos) {
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/* shrink table to half size by throwing away each second bag. */
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for (i = 1; i < XING_NUM_BAGS; i += 2)
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mp3->bag[i / 2] = mp3->bag[i];
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/* double wanted amount per bag. */
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mp3->want *= 2;
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/* adjust current position to half of table size. */
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mp3->pos = XING_NUM_BAGS / 2;
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}
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mp3->seen = 0;
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}
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}
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static int mp3_write_audio_packet(AVFormatContext *s, AVPacket *pkt)
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{
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MP3Context *mp3 = s->priv_data;
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if (mp3->xing_offset && pkt->size >= 4) {
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MPADecodeHeader c;
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avpriv_mpegaudio_decode_header(&c, AV_RB32(pkt->data));
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if (!mp3->initial_bitrate)
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mp3->initial_bitrate = c.bit_rate;
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if ((c.bit_rate == 0) || (mp3->initial_bitrate != c.bit_rate))
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mp3->has_variable_bitrate = 1;
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mp3_xing_add_frame(mp3, pkt);
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}
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return ff_raw_write_packet(s, pkt);
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}
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static int mp3_queue_flush(AVFormatContext *s)
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{
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MP3Context *mp3 = s->priv_data;
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@ -162,7 +243,7 @@ static int mp3_queue_flush(AVFormatContext *s)
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mp3_write_xing(s);
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while ((pktl = mp3->queue)) {
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if (write && (ret = ff_raw_write_packet(s, &pktl->pkt)) < 0)
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if (write && (ret = mp3_write_audio_packet(s, &pktl->pkt)) < 0)
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write = 0;
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av_free_packet(&pktl->pkt);
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mp3->queue = pktl->next;
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@ -172,30 +253,50 @@ static int mp3_queue_flush(AVFormatContext *s)
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return ret;
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}
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static void mp3_update_xing(AVFormatContext *s)
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{
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MP3Context *mp3 = s->priv_data;
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int i;
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/* replace "Xing" identification string with "Info" for CBR files. */
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if (!mp3->has_variable_bitrate) {
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avio_seek(s->pb, mp3->xing_offset, SEEK_SET);
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ffio_wfourcc(s->pb, "Info");
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}
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avio_seek(s->pb, mp3->xing_offset + 8, SEEK_SET);
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avio_wb32(s->pb, mp3->frames);
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avio_wb32(s->pb, mp3->size);
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avio_w8(s->pb, 0); // first toc entry has to be zero.
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for (i = 1; i < XING_TOC_SIZE; ++i) {
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int j = i * mp3->pos / XING_TOC_SIZE;
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int seek_point = 256LL * mp3->bag[j] / mp3->size;
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avio_w8(s->pb, FFMIN(seek_point, 255));
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}
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avio_seek(s->pb, 0, SEEK_END);
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}
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static int mp3_write_trailer(struct AVFormatContext *s)
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{
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uint8_t buf[ID3v1_TAG_SIZE];
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MP3Context *mp3 = s->priv_data;
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if (mp3 && mp3->pics_to_write) {
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if (mp3->pics_to_write) {
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av_log(s, AV_LOG_WARNING, "No packets were sent for some of the "
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"attached pictures.\n");
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mp3_queue_flush(s);
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}
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/* write the id3v1 tag */
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if (mp3 && mp3->write_id3v1 && id3v1_create_tag(s, buf) > 0) {
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if (mp3->write_id3v1 && id3v1_create_tag(s, buf) > 0) {
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avio_write(s->pb, buf, ID3v1_TAG_SIZE);
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}
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/* write number of frames */
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if (mp3 && mp3->nb_frames_offset) {
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avio_seek(s->pb, mp3->nb_frames_offset, SEEK_SET);
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avio_wb32(s->pb, s->streams[mp3->audio_stream_idx]->nb_frames);
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avio_seek(s->pb, 0, SEEK_END);
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}
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avio_flush(s->pb);
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if (mp3->xing_offset)
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mp3_update_xing(s);
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return 0;
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}
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@ -209,7 +310,6 @@ AVOutputFormat ff_mp2_muxer = {
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.audio_codec = AV_CODEC_ID_MP2,
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.video_codec = AV_CODEC_ID_NONE,
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.write_packet = ff_raw_write_packet,
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.write_trailer = mp3_write_trailer,
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.flags = AVFMT_NOTIMESTAMPS,
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};
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#endif
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@ -251,7 +351,7 @@ static int mp3_write_packet(AVFormatContext *s, AVPacket *pkt)
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mp3->queue = pktl;
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mp3->queue_end = pktl;
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} else
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return ff_raw_write_packet(s, pkt);
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return mp3_write_audio_packet(s, pkt);
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} else {
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int ret;
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